:root,
[data-theme="mocha"] {
    --bg:         #1e1e2e;
    --crust:      #11111b;
    --surface-0:  #313244;
    --surface-1:  #45475a;
    --surface-2:  #585b70;
    --text:       #cdd6f4;
    --accent:     #fab387;
    --success:    #f9e2af;
    --error:      #f38ba8;
}
[data-theme="nord"] {
    --bg:         #2e3440;
    --crust:      #242933;
    --surface-0:  #3b4252;
    --surface-1:  #434c5e;
    --surface-2:  #4c566a;
    --text:       #eceff4;
    --accent:     #88c0d0;
    --success:    #a3be8c;
    --error:      #bf616a;
}
[data-theme="gruvbox"] {
    --bg:         #282828;
    --crust:      #1d2021;
    --surface-0:  #3c3836;
    --surface-1:  #504945;
    --surface-2:  #665c54;
    --text:       #ebdbb2;
    --accent:     #fe8019;
    --success:    #b8bb26;
    --error:      #fb4934;
}
[data-theme="everforest"] {
    --bg:         #2d353b;
    --crust:      #232a2e;
    --surface-0:  #343f44;
    --surface-1:  #3d484d;
    --surface-2:  #475258;
    --text:       #d3c6aa;
    --accent:     #a7c080;
    --success:    #dbbc7f;
    --error:      #e67e80;
}
[data-theme="dracula"] {
    --bg:         #282a36;
    --crust:      #21222c;
    --surface-0:  #383a59;
    --surface-1:  #44475a;
    --surface-2:  #6272a4;
    --text:       #f8f8f2;
    --accent:     #bd93f9;
    --success:    #50fa7b;
    --error:      #ff5555;
}
[data-theme="tokyonight"] {
    --bg:         #1a1b26;
    --crust:      #16161e;
    --surface-0:  #24283b;
    --surface-1:  #414868;
    --surface-2:  #565f89;
    --text:       #c0caf5;
    --accent:     #7aa2f7;
    --success:    #9ece6a;
    --error:      #f7768e;
}
[data-theme="latte"] {
    --bg:         #eff1f5;
    --crust:      #dce0e8;
    --surface-0:  #ccd0da;
    --surface-1:  #bcc0cc;
    --surface-2:  #acb0be;
    --text:       #4c4f69;
    --accent:     #fe640b;
    --success:    #40a02b;
    --error:      #e64553;
}
[data-theme="github-light"] {
    --bg:         #ffffff;
    --crust:      #f6f8fa;
    --surface-0:  #eaeef2;
    --surface-1:  #d0d7de;
    --surface-2:  #afb8c1;
    --text:       #24292f;
    --accent:     #0969da;
    --success:    #1a7f37;
    --error:      #cf222e;
}
[data-theme="gruvbox-light"] {
    --bg:         #fbf1c7;
    --crust:      #f2e5bc;
    --surface-0:  #ebdbb2;
    --surface-1:  #d5c4a1;
    --surface-2:  #bdae93;
    --text:       #3c3836;
    --accent:     #af3a03;
    --success:    #79740e;
    --error:      #9d0006;
}
[data-theme="rose-pine-dawn"] {
    --bg:         #faf4ed;
    --crust:      #f2e9de;
    --surface-0:  #fffaf3;
    --surface-1:  #dfdad9;
    --surface-2:  #cecacd;
    --text:       #575279;
    --accent:     #907aa9;
    --success:    #56949f;
    --error:      #b4637a;
}
:root {
    --radius: 6px;
    --transition: 0.15s ease;
}
::selection {
    background: var(--accent);
    color: var(--crust);
}
*, *::before, *::after {
    box-sizing: border-box;
}
body {
    font-family: ui-monospace, 'Cascadia Code', 'Source Code Pro', Menlo, Consolas, monospace;
    max-width: 800px;
    margin: 40px auto;
    padding: 0 20px;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    @media (max-width: 640px) {
        margin: 20px auto;
        padding: 0 16px;
    }
}
h1, h2, h3 {
    color: var(--text);
    margin-top: 1.5em;
    margin-bottom: 0.5em;
    line-height: 1.2;
}
h1 {
    border-bottom: 1px solid var(--surface-2);
    padding-bottom: 10px;
}
a {
    color: var(--accent);
    text-decoration: none;
    transition: opacity var(--transition);
    &:hover {
        text-decoration: underline;
    }
}
blockquote {
    border-left: 3px solid var(--accent);
    margin: 16px 0;
    padding: 6px 14px;
    background: var(--surface-0);
    border-radius: 0 var(--radius) var(--radius) 0;
    color: var(--text);
    & p {
        margin: 0;
    }
}
pre {
    background: var(--crust);
    padding: 14px 16px;
    border: 1px solid var(--surface-2);
    border-radius: var(--radius);
    overflow-x: auto;
    width: fit-content;
    max-width: 100%;
    margin: 16px 0;
    @media (max-width: 640px) {
        width: 100%;
    }
    & code {
        background: transparent;
        padding: 0;
        border: none;
    }
}
code {
    background: var(--surface-0);
    padding: 2px 6px;
    border: 1px solid var(--surface-1);
    border-radius: var(--radius);
    font-size: 0.9em;
    word-break: break-word;
}
ul, ol {
    list-style: none;
    padding: 0;
    margin: 16px 0;
    & li {
        position: relative;
        padding-left: 28px;
        margin-bottom: 10px;
        line-height: 1.6;
    }
    & ul, & ol {
        margin: 4px 0 6px 0;
        padding-left: 12px;
    }
}
ol {
    counter-reset: list-counter;
    & > li::before {
        counter-increment: list-counter;
        content: counter(list-counter) ".";
        position: absolute;
        left: 2px;
        color: var(--accent);
        font-weight: bold;
        font-family: inherit;
    }
}
ul > li::before {
    content: "-";
    position: absolute;
    left: 2px;
    color: var(--accent);
    font-weight: bold;
}
input, button, select {
    font-family: inherit;
    font-size: 0.9rem;
    padding: 8px 12px;
    background: var(--crust);
    color: var(--text);
    border: 1px solid var(--surface-2);
    border-radius: var(--radius);
    transition: border-color var(--transition), background-color var(--transition);
    max-width: 100%;
    @media (max-width: 640px) {
        padding: 10px 12px;
    }
    &:hover {
        border-color: var(--accent);
    }
    &:focus-visible {
        outline: 2px solid var(--accent);
        outline-offset: 2px;
    }
    &:disabled {
        opacity: 0.6;
        cursor: not-allowed;
        border-color: var(--surface-1);
    }
}
button {
    cursor: pointer;
    color: var(--accent);
    white-space: normal;
    text-align: center;
    &:hover {
        background: var(--surface-0);
    }
    &:active {
        transform: translateY(1px);
    }
}
select {
    appearance: none;
    -webkit-appearance: none;
    -moz-appearance: none;
    padding-right: 28px;
    cursor: pointer;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6' viewBox='0 0 10 6'%3E%3Cpath fill='%23a6adc8' d='M0 0l5 6 5-6z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 10px center;
    & optgroup {
        background-color: var(--crust);
        color: var(--accent);
        font-weight: bold;
    }
    & option {
        background: var(--crust);
        color: var(--text);
    }
}
input[type="number"] {
    -moz-appearance: textfield;
    &::-webkit-inner-spin-button, &::-webkit-outer-spin-button {
        -webkit-appearance: none;
        margin: 0;
    }
}
nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 14px;
    border-bottom: 1px dashed var(--surface-2);
    padding-bottom: 16px;
    margin-bottom: 32px;
    @media (max-width: 640px) {
        flex-direction: column;
        align-items: flex-start;
        gap: 16px;
    }
}
.nav-controls {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
    @media (max-width: 640px) {
        width: 100%;
        justify-content: space-between;
        gap: 12px;
    }
}
.nav-item {
    display: flex;
    align-items: center;
    gap: 8px;
    @media (max-width: 640px) {
        flex-direction: column;
        align-items: flex-start;
        gap: 6px;
        width: 100%;
        & select, & input {
            width: 100% !important;
        }
    }
}
.nav-label {
    font-size: 0.85rem;
    color: var(--surface-2);
}
.star-counter {
    color: var(--success);
    font-weight: bold;
    font-size: 0.95rem;
    letter-spacing: 1px;
}
footer {
    margin-top: 64px;
    padding-top: 24px;
    border-top: 1px dashed var(--surface-2);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
    font-size: 0.85rem;
    color: var(--surface-2);
    @media (max-width: 640px) {
        flex-direction: column;
        text-align: center;
        gap: 12px;
    }
    & .footer-right {
        display: flex;
        gap: 16px;
        @media (max-width: 640px) {
            justify-content: center;
            width: 100%;
        }
    }
    & a {
        color: var(--surface-2);
        text-decoration: none;
        transition: color var(--transition);
        &:hover {
            color: var(--accent);
            text-decoration: underline;
        }
    }
}
.challenge-container {
    margin-top: 24px;
}
.input-download-box {
    display: flex;
    flex-direction: column;
    gap: 12px;
    margin: 24px 0;
}
#challenge-input {
    margin: 0;
    width: 100%;
    color: var(--surface-2);
}
.part-form-box {
    background: var(--surface-0);
    padding: 18px 20px;
    border: 1px solid var(--surface-1);
    border-radius: var(--radius);
    margin: 24px 0;
}
.answer-form {
    display: flex;
    align-items: center;
    gap: 10px;
    flex-wrap: wrap;
    & input {
        width: 220px;
        font-size: 1rem;
    }
    @media (max-width: 640px) {
        & input, & button {
            width: 100%;
        }
    }
}
#result-msg, #result-msg-1, #result-msg-2 {
    font-size: 0.95rem;
    margin-left: 6px;
    &:empty {
        display: none;
    }
}
.success {
    color: var(--success);
    font-weight: bold;
}
.fail {
    color: var(--error);
    font-weight: bold;
}
.part-2-locked {
    display: none;
}
.part-2-unlocked {
    display: block;
    animation: fadeInPart2 0.4s ease-out;
    margin-top: 36px;
    padding-top: 24px;
    border-top: 1px dashed var(--surface-2);
}
.calendar-month {
    margin-bottom: 48px;
}
.month-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--surface-2);
    padding-bottom: 10px;
    margin-bottom: 20px;
    margin-top: 32px;
    & h2 {
        margin: 0;
        font-size: 1.35rem;
    }
}
.month-overview-link {
    font-size: 0.88rem;
}
.calendar-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
    gap: 14px;
}
.calendar-card {
    background: var(--surface-0);
    border: 1px solid var(--surface-1);
    border-radius: var(--radius);
    padding: 14px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    min-height: 110px;
    text-decoration: none;
    transition: transform var(--transition), border-color var(--transition), background-color var(--transition);
    &:hover {
        border-color: var(--accent);
        background-color: var(--crust);
        transform: translateY(-2px);
        text-decoration: none;
    }
    &.stars-1 {
        border-color: var(--surface-2);
        & .star-1 {
            color: #e0e0e0;
            text-shadow: 0 0 6px rgba(255, 255, 255, 0.35);
        }
    }
    &.stars-2 {
        border-color: var(--success);
        & .star-1, & .star-2 {
            color: var(--success);
            text-shadow: 0 0 8px var(--success);
        }
    }
    &.locked {
        opacity: 0.45;
        cursor: not-allowed;
        background: var(--crust);
        border-style: dashed;
        &:hover {
            transform: none;
            border-color: var(--surface-1);
        }
        & .calendar-day-num {
            color: var(--surface-2);
        }
    }
}
.calendar-card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
}
.calendar-day-num {
    font-size: 1.6rem;
    font-weight: bold;
    color: var(--accent);
    line-height: 1;
}
.calendar-day-title {
    font-size: 0.85rem;
    color: var(--text);
    margin-top: 10px;
    line-height: 1.3;
}
.calendar-stars {
    font-size: 0.85rem;
    letter-spacing: 2px;
    & .star {
        color: var(--surface-2);
        transition: color var(--transition), text-shadow var(--transition);
    }
}
.calendar-lock {
    font-size: 0.85rem;
}
@keyframes fadeInPart2 {
    from {
        opacity: 0;
        transform: translateY(12px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}
::-webkit-scrollbar-track {
    background: var(--crust);
}
::-webkit-scrollbar-thumb {
    background: var(--surface-1);
    border-radius: var(--radius);
    &:hover {
        background: var(--surface-2);
    }
}